Glass ribbons are produced in various downdraw glass manufacturing processes, e.g., the fusion downdraw process, as well as in the float process. The tension in the ribbon and, in particular, the across-the-ribbon tension, is important in controlling the flatness of the ribbon as well as the residual stress in individual glass sheets produced from the ribbon. The across-the-ribbon tension can be controlled by, for example, contacting the surface of the ribbon with rollers oriented at an angle to the direction of motion of the ribbon (referred to herein as “stub rollers” or “stub rolls”). Such rollers stabilize the ribbon and apply a tension force to the ribbon in the across-the-ribbon direction, as well as a “pinch” force in a direction normal to the surface of the ribbon.
Prior to the present disclosure, there has been no known method of monitoring the forces exerted on the ribbon by such rollers. The present disclosure provides methods and apparatus for monitoring these forces in real time without adversely affecting the glass forming process. The data provided by these methods and apparatus can, for example, be used to provide feedback to process engineers so that adjustments can be made to the forming process, including adjustments that result in improved glass attributes, e.g., lower residual stress levels.